3D Seismic Isolation Research Articles

Current status of development in the 3D seismic isolation applied to SFRs

Current status of development in the 3D seismic isolation applied to SFRs

Performance of flexible frame building with horizontal and 3D seismic isolation when subjected to 3D ground shaking

Seismic isolation is known to effectively mitigate the effects of horizontal ground shaking in building structures. Recent research has suggested that vertical excitation causes high-intensity slab vibrations that lead to nonstructural component damage. A detailed case study of the application of three-dimensional (3D) isolation in a realistic multi-story frame building is presented. Specifically, the seismic responses of hypothetical special concentric braced frame buildings with horizontal and 3D isolation are compared to evaluate the effectiveness of 3D isolation to mitigate the vertical ground shaking. Overall, 3D isolation with a relatively short isolation period (0.5 s) is adequate to significantly mitigate the vertical acceleration in a flexible frame building, including the amplification at mid-slab relative to adjacent columns, without compromising the usual reductions in horizontal responses.

Static Test and Seismic Dynamic Response of an Innovative 3D Seismic Isolation System

Seismic isolation is an efficient strategy to protect structures from the effects of moderate to severe earthquake shaking. Conventional isolation devices can reduce the structural response in horizontal directions only; however, three-dimensional (3D) ground motions have been observed in earthquake records. In this paper, an innovative 3D seismic isolator is proposed. A new kind of asymmetric oblique hysteretic model is illustrated, and a quasistatic compression test of a model device using three lead rubber bearings (LRBs) is conducted. The test results and theoretical model results match well. A significant asymmetric property is observed in the hysteretic curves. The proposed hysteretic model can efficiently simulate the vertical mechanical behavior of a 3D seismic isolation system. The effects of different parameters are highlighted based on the theoretical mechanical model. The inclination angle, friction coefficient, and second shape factor of the inclined LRBs strongly influence the vertical behavior of the proposed device. A dynamic response analysis of the substructure of a nuclear power plant (NPP) is conducted. The hysteretic curves have the shape of an asymmetric quadrangle; this shape is similar to that observed in the test results. The vertical acceleration response of the vertical isolation structure is reduced by 33% compared with that of a fixed-base structure and reduced by 58% compared with that of a horizontal isolation structure. The proposed 3D isolator can sufficiently isolate the seismic input.

Application and design of 3D seismic isolation bearing in lattice shell structure

ABSTRACTA three-dimensional seismic isolation bearing (3DSIB) was introduced. The 3DSIB was designed and applied in a single-layer spherical lattice shell structure with 40 m span by using a SAP2000 software. The original record of the Taft seismic wave was input into the shell structure in X, Y and Z directions, respectively in the model. The effectiveness of the 3DSIB was examined by time history analysis to the shell structural model in the SAP2000. It was shown that the isolated structure with 3DSIBs had better performance compared with the un-isolated structure in terms of the nodal absolute acceleration response as well as member axial force. It was found that the 3DSIB had good isolation function in both horizontal and vertical directions for shell structure under seismic conditions. Furthermore, the influence of horizontal and vertical stiffness of 3DSIB on the structural period, structural member peak axial force and nodal absolute acceleration were analysed. The variation of the structural respo...

433 発電用新型炉へ適用する3次元免震システムの研究 : 開発計画の検討:その5

Mitigation of the earthquake loads by seismic isolation technology is very promising for enhanced safety and economy of the next generation nuclear power plant. A research for 3D seismic isolation technologies has been conducted under the sponsorship of the Ministry of Economy, Trade and Industry. Two types of 3D seismic isolation systems were developed. One is the 3D entire building base isolation system. The other is the vertical isolation system for main components in the horizontally entire building base isolation. For the former technology, the "rolling seal type air spring + hydraulic rocking suppression system" is selected after several studies. For the latter, the coned disk spring system is adopted. The reduced models of the two systems were tested on the shake tables. The test results show that the two systems satisfy the requirements of isolation and are applicable to the plant.

102 発電用新型炉へ適用する3次元免震システムの研究 : 開発計画の検討:その4(免震構造1,OS-12:耐震・免震・制振(1))

Mitigation of earthquake loads by seismic isolation technology is very promising for enhanced safety and economy of the next generation nuclear reactors. A research project has been undertaken for the development of 3D seismic isolation technology, under the sponsorship of the Ministry of Economy, Trade and Industry. There are two types of 3D seismic isolation system concept. One is the 3D entire building base isolation technology and another is the vertical isolation device for main component with horizontally entire building base isolation technology. For the former technology, three types of system concept were nominated. These are "Hydraulic 3D base isolation system", "Independent cable reinforced rolling-seal air spring" and "Rolling seal type air spring". This paper reports the performance requirements for 3D isolation system and the criteria for the system selection.